It is desirable in word processing equipment having a display to generate an image on the display which replicates, as near as possible, the information which is ultimately printed on a document. This accurate replication includes the attributes of the characters ultimately printed on the document. Typical printed character attributes include bolded characters, underscored characters and double underscored characters.
Character attributes have been exhibited in the past in word processing equipment. These character attributes have been exhibited, however, in a manner which typically differs from the form they are printed on the document. As an example, one system uses a bold character on a display to signify that the character on the printed document is to be underlined. Additionally, other word processing equipment display attributes by the exhibition of control information on the screen.
In U.S. Pat. No. 4,057,849 granted to Ying, et al, a system is disclosed which supports several character attributes on a display. These character attributes include reverse video, bold, blinking and single underline. These character attributes, however, are incorporated in the information for each alphanumeric character as text characters defining words stored in sequence in the memory; they are not stored in a separate storage memory, thus requiring additional storage space. Moreover, the character attributes are not an accurate replication of the attribute or character printed on the page. In proportional printing, for example, character widths vary. Thus, the letter "M" occupies a greater space than the letter "i". Consequently, the character attribute displayed by the word processing equipment must similarly be a proportional representation. The structure disclosed in the aforementioned patent does not provide the ability to achieve this objective.